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2 years ago

Find the total area for the regular pyramid.

Mathematics

1 answer:

hram777 [196]2 years ago

3 0

Answer:

Option B

Step-by-step explanation:

Given is the hexagonal pyramid.

We know the radius of the base is same as its side.

Find the base area:

A = 3√3/2a²
A = 3√3/2*6² = 54√3

Given the height and radius, find the side of the lateral triangular faces:

$\sqrt{8^2+6^2} =\sqrt{100} =10$

Each of 6 triangles have sides 10, 10 and 6 units.

Find the area using heron's formula:

s = P/2 = (10*2 + 6)/2 = 13
s - a = s - b = 13 - 10 = 3
s - c = 13 - 6 = 7
$A = \sqrt{s(s-a)(s-b)(s-c)} =\sqrt{13*3*3*7} =3\sqrt{91}$

Total surface area:

$S = 6*3\sqrt{91}+54\sqrt{3} =18\sqrt{91}+54\sqrt{3}$

Correct choice is B

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Considering the number of questions incorrect from classmates on a quiz {10, 11, 12, 13, 13, 13, 14, 15, 16, 16, 17, 18, 18, 19,

IrinaK [193]

Answer:

According to the Empirical Rule, 68% of the data should fall between 11.98 and 18.02

Step-by-step explanation:

We are given the following data in the question:

10, 11, 12, 13, 13, 13, 14, 15, 16, 16, 17, 18, 18, 19, 20

Formula:

$\text{Standard Deviation} = \sqrt{\displaystyle\frac{\sum (x_i -\bar{x})^2}{n-1}}$

where $x_i$ are data points, $\bar{x}$ is the mean and n is the number of observations.

$Mean = \displaystyle\frac{\text{Sum of all observations}}{\text{Total number of observation}}$

$Mean =\displaystyle\frac{225}{15} = 15$

Sum of squares of differences = 25 + 16 + 9 + 4 + 4+ 4 + 1 + 0+ 1+ 1 + 4 + 9 + 9+ 16 + 25 = 128

$S.D = \sqrt{\dfrac{128}{14}} = 3.02$

Empirical rule:

According to this rule almost all the data lies within three standard deviation of the mean for a normal distribution.
About 68% of data lies within one standard deviation of the mean.
About 95% of data lies within two standard deviations of mean.
Arround 99.7% of data lies within three standard deviation of mean.

Thus, by empirical rule,

$\mu \pm 1\sigma = 15\pm (3.02) = (11.98,18.02)$

According to the Empirical Rule, 68% of the data should fall between 11.98 and 18.02

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3 years ago

Jose’s school has 426 students. His principal has promised the Student Council that their idea will be carried out if they can g

Kryger [21]

Answer: Step 4

Step-by-step explanation:

1. Define variable x as student signatures still needed (Correct)

$2)\ \dfrac{x+82}{426}$ (Correct)

3. 25% = 0.25 (Correct)

$4)\ \dfrac{x+82}{426}\leq 0.25$ (Error)!

The inequality symbol should be GREATER THAN or equal to (≥) because Jose needs 25% or more (not less).

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3 years ago

Read 2 more answers

if area of a circle varies directly as the cube of the radius, when the area is 625cm the radius is 5cm. calculate the area of a

Maksim231197 [3]

Answer:

as the above condition....

5×5×5=625

same,, applying for 8 cm

8×8×8=512cm..

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3 years ago

The projected sales volume of a video game cartridge is given by the function s(p) = 3000 / (2p + a), where s is the number of c

Alex_Xolod [135]

Answer: 149 cartridges will be sold at 20 dollars per cartridge.

Step-by-step explanation:

Given: The projected sales volume of a video game cartridge is given by the function $s(p)=\dfrac{3000}{2p+a}$ , where s is the number of cartridges sold, in thousands; p is the price per cartridge, in dollars; and a is a constant.

Put s(p)=100000, p= 10, we get

$100000=\dfrac{3000}{2(10)+a}\\\\\Rightarrow\ 100=\dfrac{3}{20+a}\\\\\Rightarrow\ 100(20+a)=3\\\\\Rightarrow\ 2000+100a=3\\\\\Rightarrow\ 100a=-1997\\\\\Rightarrow\ a=-19.97$

i.e. $s(p)=\dfrac{3000}{2p-19.97}$

Put p=20, we get

$s(20)=\dfrac{3000}{2(20)-19.97}\\\\=\dfrac{3000}{40-19.97}\\\\=\dfrac{3000}{20.03}\approx149$

Hence, 149 cartridges will be sold at 20 dollars per cartridge.

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3 years ago

Estimate. Then find the product 7 x 456

Novosadov [1.4K]

3,500 is the best estimate if you multiply 7 by round 456 to 500 so 7x500=3,500

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3 years ago